Method of manufacturing a screen cylinder and a screen cylinder

Abstract

The present invention relates to a method of manufacturing a screen cylinder, and a screen cylinder that is particularly suitable for screening, filtering, fractionating, or sorting cellulose pulp suspensions of the pulp and paper making industry, or other similar suspensions. The present invention relates more particularly to a screen cylinder formed from a plurality of screen wires leaving screening slots therebetween, and circular support elements. The support elements include openings/grooves for installation of the screen wires therein, so that at least one of the support rings is thermally deformed and clamps the screen wires in the openings/grooves of the rings.

1. A method of manufacturing a screen cylinder, said screen cylinder comprising a plurality of screen wires having screening slots therebetween, and substantially circular support rings, said support rings having openings for receiving said screen wires, wherein the method comprises:
 a) installing the screen wires in said openings of said support rings, 
 b) heating at least one of said rings to thermally expand the ring unevenly, and 
 c) allowing said at least one ring to cool, whereby the ring retracts unevenly clamping the screen wires in said openings. 
 
     
     
       2. The method as recited in  claim 1 , wherein said heating comprises temporarily and locally heating the support ring to between 450 and 900 degrees Celsius. 
     
     
       3. The method as recited in  claim 1 , wherein the heating is performed with a welding torch. 
     
     
       4. The method as recited in  claim 1 , wherein the method further comprises, before step b), positioning the cylinder on rolls, and, during step b), rotating the cylinder. 
     
     
       5. The method as recited in  claim 1 , wherein heating comprises heating all of the support rings. 
     
     
       6. The method as recited in  claim 1 , wherein the method further comprises, prior to step b), positioning a heat shield on the screen wires. 
     
     
       7. The method as recited in  claim 1 , wherein the openings are adapted to allow form-locking of the screen wires in the support rings. 
     
     
       8. The method as recited in  claim 3 , wherein the method further comprises, prior to step b), positioning a heat shield on the screen wires. 
     
     
       9. The method as recited in  claim 1 , wherein the openings comprise grooves. 
     
     
       10. The method as recited in  claim 1 , wherein said at least one of said rings comprises a lateral face, and wherein heating comprises locally heating said lateral face. 
     
     
       11. The method as recited in  claim 1 , wherein heating at least one of said rings comprises locally heating at least one of said rings. 
     
     
       12. The method as recited in  claim 1 , wherein heating at least one of said rings comprises heating to thermally expand a free rim of the support ring so that the free rim bends upwards. 
     
     
       13. The method as recited in  claim 12 , wherein said allowing said at least one ring to cool comprises allowing said at least one ring to cool and bend downward past an original unheated position.